diff options
authorJason Gunthorpe <jgg@nvidia.com>2020-10-16 08:46:01 -0300
committerJason Gunthorpe <jgg@nvidia.com>2020-10-16 12:41:33 -0300
commit9a40401cfa1356b0d169be8470ed7b2edc33b98f (patch)
parent16e7483e6f02973972f832b18042fd6c45fe26c0 (diff)
lib/scatterlist: Do not limit max_segment to PAGE_ALIGNED values
The main intention of the max_segment argument to __sg_alloc_table_from_pages() is to match the DMA layer segment size set by dma_set_max_seg_size(). Restricting the input to be page aligned makes it impossible to just connect the DMA layer to this API. The only reason for a page alignment here is because the algorithm will overshoot the max_segment if it is not a multiple of PAGE_SIZE. Simply fix the alignment before starting and don't expose this implementation detail to the callers. A future patch will completely remove SCATTERLIST_MAX_SEGMENT. Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
1 files changed, 8 insertions, 4 deletions
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index e102fdfaa75b..ed2497c79a21 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -404,7 +404,7 @@ static struct scatterlist *get_next_sg(struct sg_table *table,
* @n_pages: Number of pages in the pages array
* @offset: Offset from start of the first page to the start of a buffer
* @size: Number of valid bytes in the buffer (after offset)
- * @max_segment: Maximum size of a scatterlist node in bytes (page aligned)
+ * @max_segment: Maximum size of a scatterlist element in bytes
* @prv: Last populated sge in sgt
* @left_pages: Left pages caller have to set after this call
* @gfp_mask: GFP allocation mask
@@ -435,7 +435,12 @@ struct scatterlist *__sg_alloc_table_from_pages(struct sg_table *sgt,
unsigned int added_nents = 0;
struct scatterlist *s = prv;
- if (WARN_ON(!max_segment || offset_in_page(max_segment)))
+ /*
+ * The algorithm below requires max_segment to be aligned to PAGE_SIZE
+ * otherwise it can overshoot.
+ */
+ max_segment = ALIGN_DOWN(max_segment, PAGE_SIZE);
+ if (WARN_ON(max_segment < PAGE_SIZE))
return ERR_PTR(-EINVAL);
@@ -542,8 +547,7 @@ int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
unsigned long size, gfp_t gfp_mask)
return PTR_ERR_OR_ZERO(__sg_alloc_table_from_pages(sgt, pages, n_pages,
- NULL, 0, gfp_mask));
+ offset, size, UINT_MAX, NULL, 0, gfp_mask));

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